System and method for detection enhancement programming

ABSTRACT

A system and method of enabling detection enhancements selected from a plurality of detection enhancements. In a system having a plurality of clinical rhythms, including a first clinical rhythm, where each of the detection enhancements is associated with the clinical rhythms, the first clinical rhythm is selected. The first clinical rhythm is associated with first and second detection enhancements. When the first clinical rhythm is selected, parameters of the first and second detection enhancements are set automatically. A determination is made as to whether changes are to be made to the parameters. If so, one or more of the parameters are modified under user control.

CROSS REFERENCE TO RELATED APPLICATION

[0001] This application is a continuation of U.S. application Ser. No.09/569,928, filed on May 13, 2000, the specification of which isincorporated by reference herein.

FIELD OF THE INVENTION

[0002] The present invention is related to implantable cardioverterdefibrillator therapy, and more particularly to a system and method fordisplaying and selecting detection enhancements within a cardioverterdefibrillator.

BACKGROUND INFORMATION

[0003] Detection enhancements are used in implantable cardioverterdefibrillator therapy to reduce the incidence of inappropriate shocks.In the past, defibrillators were only rate derivative. If the patient'sheart rate crossed over the prescribed rate, a shock was delivered tothe heart. Experience showed that the heart could pass through theprescribed rate for a variety of reasons, only some of which warrantedshocking the heart. For instance, the heart could beat faster duringexercise, or because the person was excited, or even due to atrialarrhythmia. None of these warrant shock therapy.

[0004] Detection enhancements are sets of rules for determining when todeliver shock therapy. These rules may, for instance, look not only atthe change in rate but also at the source of the arrhythmia, at thesuddenness of onset or at the stability of the heart beat.

[0005] In the past, detection enhancements were treated as separateitems on a laundry list of possible detection enhancements. The languageused to describe the features was often a reflection of the programmingcode used to implement the features. Such an approach was confusing tophysicians. As a result, physicians either ignored the enhancements orstruggled with programming the detection enhancements into the patient'sdefibrillator.

[0006] What is needed is a system and method for displaying andselecting detection enhancements within a cardioverter defibrillatorwhich addresses these deficiencies.

SUMMARY OF THE INVENTION

[0007] According to one aspect of the present invention, a system andmethod of enabling detection enhancements selected from a plurality ofdetection enhancements is described. In a system having a plurality ofclinical rhythms, including a first clinical rhythm, where each of thedetection enhancements is associated with the clinical rhythms, thefirst clinical rhythm is selected. The first clinical rhythm isassociated with first and second detection enhancements. When the firstclinical rhythm is selected, parameters of the first and seconddetection enhancements are set automatically. A determination is made asto whether changes are to be made to the parameters. If so, one or moreof the parameters are modified under user control.

[0008] According to another aspect of the present invention, a systemand method of programming one or more detection enhancements into adefibrillator is described. In a system having a plurality of clinicalrhythms, including a first clinical rhythm, where each of the detectionenhancements is associated with the clinical rhythms, the first clinicalrhythm is selected. The first clinical rhythm is associated with firstand second detection enhancements. When the first clinical rhythm isselected, parameters of the first and second detection enhancements areset automatically. A determination is made as to whether changes are tobe made to the parameters. If so, one or more of the parameters aremodified under user control. The defibrillator is then programmed toperform the first and second detection enhancements as a function of theparameters.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] In the drawings, where like numerals refer to like componentsthroughout the several views:

[0010]FIG. 1 illustrates an implantable cardioverter defibrillatorwithin a shock therapy system;

[0011]FIG. 2 illustrates a method of selecting detection enhancementsfrom a plurality of possible detection enhancements and of modifyingparameters associated with the selected detection enhancements;

[0012]FIG. 3 illustrates one embodiment of the system of FIG. 1;

[0013]FIG. 4 illustrates display showing a representative three zoneconfiguration;

[0014]FIG. 5 illustrates detection enhancements availability withinzones of a multi-zone configuration;

[0015]FIG. 6 illustrates AFib Rate Threshold and Stability interaction;

[0016]FIG. 7 illustrates representative Onset, Stability and AFib Ratecombinations and the suggested therapy;

[0017]FIG. 8 illustrates representative Onset and Stability combinationsand the suggested therapy;

[0018]FIG. 9 illustrates Sustained Rate Duration in relation toinhibitor enhancements;

[0019]FIG. 10 illustrates detection enhancement details for VT-1 zone;

[0020]FIG. 11 illustrates rhythm discrimination available per zone inmulti-zone configurations;

[0021]FIGS. 12 and 13 illustrate one embodiment of pre-selectedparameter values suitable for detection enhancements by clinical rhythm;

[0022]FIG. 14,illustrates detection enhancement details for VT-1 zone;

[0023]FIG. 15 illustrates a display emphasizing VT zone parameterswithin a multi-zone configuration;

[0024]FIG. 16 illustrates detection enhancement details for VT zone;

[0025]FIG. 17 illustrates one embodiment of a display; and

[0026]FIG. 18 illustrates one embodiment of a display.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] In the following detailed description of the preferredembodiments, reference is made to the accompanying drawings which form apart hereof, and in which is shown by way of illustration specificembodiments in which the invention may be practiced. It is to beunderstood that other embodiments may be utilized and structural changesmay be made without departing from the scope of the present invention.

[0028] Some portions of the detailed descriptions which follow arepresented in terms of algorithms and symbolic representations ofoperations on data bits within a computer memory. These algorithmicdescriptions and representations are the means used by those skilled inthe data processing arts to most effectively convey the substance oftheir work to others skilled in the art. An algorithm is here, andgenerally, conceived to be a self-consistent sequence of steps leadingto a desired result. The steps are those requiring physicalmanipulations of physical quantities. Usually, though not necessarily,these quantities take the form of electrical or magnetic signals capableof being stored, transferred, combined, compared, and otherwisemanipulated. It has proven convenient at times, principally for reasonsof common usage, to refer to these signals as bits, values, elements,symbols, characters, terms, numbers, or the like. It should be borne inmind, however, that all of these and similar terms are to be associatedwith the appropriate physical quantities and are merely convenientlabels applied to these quantities. Unless specifically stated otherwiseas apparent from the following discussions, it is appreciated thatthroughout the present invention, discussions utilizing terms such as“processing” or “computing” or “calculating” or “determining” or“displaying” or the like, refer to the action and processes of acomputer system, or similar electronic computing device, thatmanipulates and transforms data represented as physical (electronic)quantities within the computer system's registers and memories intoother data similarly represented as physical quantities within thecomputer system memories or registers or other such information storage,transmission or display devices.

[0029]FIG. 1 illustrates an implantable shock therapy system. Shocktherapy system 10 includes a defibrillator 12, a power supply 14 and aprogrammer 20. Power supply 14 is connected to defibrillator 12 andsupplies power to defibrillator 12.

[0030] In one such embodiment, defibrillator 12 includes a telemetrysystem 16 for communicating with programmer 20. In addition,defibrillator 12 supplies the requisite therapy to the heart via leads18.

[0031] In one embodiment, programmer 20 includes an input device 22 suchas a keyboard or mouse, a display 24 and telemetry system 26. Featuresselected or programmed by physicians into programmer 20 are communicatedthrough telemetry to defibrillator 12, where they control shock andpacing therapy applied to the patient's heart. Detection enhancementsare just some of the features programmed in this manner by thephysician.

[0032] As noted above, in the past detection enhancements were treatedas separate items on a laundry list of possible detection enhancements.The language used to describe the features was often a reflection of theprogramming code used to implement the features. Such an approach wasconfusing to physicians. As a result, physicians either ignored theenhancements or struggled while programming the detection enhancementsinto the patient's defibrillator.

[0033] As a response to this problem, programmer 20 includes controllogic which allows the physician to program all appropriate enhancementsby a process of selection. In one embodiment, the physician checks boxesthat describe the patient's arrhythmia (e.g., Atrial Fibrillation orSinus Tachycardia). In another embodiment, symbols representative of thearrhythmia are displayed to be selected by the user. For instance, ifthere are two detection enhancements that protect against sinustachycardia, a symbol labeled “sinus tachycardia protection” isdisplayed.

[0034] In one embodiment, the physician uses input device 22 to indicatethe selected arrhythmia and programmer 20 programs defibrillator 12 toperform the underlying detection enhancements. In one such embodiment,programmer 20 uses artificial intelligence to set values of parameterswithin each of the desired detection enhancements. These values may bedefault values, or can be calculated as a function of patient or therapyparameters already established in programmer 20. In one expert systemembodiment, a set of rules establish the values set for parametersprogrammed automatically by programmer 20. Such a system is describedbelow.

[0035] A system which programs detection enhancements by simply checkingclinical rhythms and letting the programmer do the rest may not beflexible enough to meet the varying demands of the real world. Toaddress this, in one embodiment, programmer 20 includes control logicwhich allows the physician to manipulate parameters associated with thedetection enhancements selected on the basis of clinical rhythms. Thisprovides the experienced physician the ability to manipulate the valuesof parameters associated with particular detection parameters, whileletting the less sophisticated user rely on the expertise of theengineers and physicians who designed the defibrillator system.

[0036] One method of selecting detection enhancements from a pluralityof possible detection enhancements and of modifying parametersassociated with the selected detection enhancements is shown in FIG. 2.Programmer 20 is programmed to include a number of different clinicalrhythms. Each clinical rhythm is associated with one or more detectionenhancements. At 30, the physician selects one or more of the availableclinical rhythms. In one embodiment, programmer 20 displays theavailable clinical rhythms on display 24 so that the physician canselect one or more clinical rhythms through input device 22. In anotherembodiment, the physician may enter the desired clinical rhythms bytyping or dictating labels corresponding to the desired rhythm intoinput device 22.

[0037] Once the one or more clinical rhythms has been selected, controlmoves to 32, where programmer 20 identifies the detection enhancementsassociated with the selected clinical rhythms and sets parametersassociated with the identified detection enhancements. Control moves to34, where a determination is made as to whether the physician wishes tomodify one or more of the detection enhancement parameters. This may bedone, for example, by directly querying the physician on display 22, orby presenting a set of options which includes a “Modify parameters”button or icon.

[0038] If a determination is made that the physician does not wish tomodify one or more of the detection enhancement parameters, controlmoves to 38, where the detection enhancement parameters are programmedinto defibrillator 12.

[0039] If a determination is made that the physician does wish to modifyone or more of the detection enhancement parameters, control moves to36, and the physician enters or modifies the desired values. Controlthen moves to the 38, where the detection enhancement parameters areprogrammed into defibrillator 12.

[0040] One embodiment of a system 10 used to deliver shock therapy to aheart is shown in FIG. 3. In FIG. 3, shock therapy system 50 includes adefibrillator 52, a programmer 54 and a communications link 56.Communications link 56 transfers data between defibrillator 52 andprogrammer 54. Embodiments of communications link 56 include wired,wireless, optical and other forms of communications.

[0041] In one such embodiment, programmer 54 includes selection module58, parameter modification module 60 and communication module 62.Selection module 58 displays the available clinical rhythms. Eachclinical rhythm is associated with one or more detection enhancements.Selection module 58 also includes a user interface which allows a userto select one or more to the clinical rhythms.

[0042] Parameter modification module 60 receives the selected clinicalrhythm from first control logic 58, stores parameters related to theassociated detection enhancements, determines if the user wishes tomodify the parameters, and, if the user modifies the parameters, storesthe modified parameters.

[0043] Communication module 62 programs defibrillator 52 to perform theassociated detection enhancements as a function of the storedparameters. Module 62 also is connected to selection module 58 in orderto display data captured by defibrillator 52.

[0044] In one embodiment, a user interface is designed for system 10 toprovide a “layering” effect. That is, the top screen is designed toprovide easy activation of the detection enhancements by displayingclinical rhythm discrimination features that the physician may wish toprogram. Parameters associated with the selected detection enhancementsare seeded with a suggested set of nominal values; the physician canchoose to accept these values or can change any or all values asdesired. If the physician chooses to change the suggested values, accessis given to an underlying screen where the specific detectionenhancements are listed, and the programming values are accessible. Withthis dual-layer approach, system 10 provides the flexibility to thephysician to either use proven, preselected values or to change thevalues to patient specific settings.

[0045] As noted above, detection enhancements are used to addspecificity to rate and duration detection criteria. In one embodiment,enhancements can be programmed to delay or inhibit therapy, to bypasstherapy inhibition, or to bypass a sequence of ATP therapy in favor ofshock therapy. Some of the available detection enhancements include VRate>A Rate, AFib Rate Threshold, Stability, Onset, Shock if Unstableand Sustained Rate Duration (SRD).

[0046] The V Rate>A Rate enhancement is used to deliver therapy anytimethe ventricular rate is greater than the atrial rate. It can also beused to bypass the Onset, Stability, and/or AFib Rate Thresholdparameters' decision to inhibit therapy.

[0047] The AFib Rate Threshold enhancement is programmed to inhibitventricular therapy if the atrial rhythm is fast. The Stabilityparameter is programmed to inhibit therapy delivery if the ventricularrhythm is unstable. Onset is programmed to inhibit therapy if thepatient's heart rate increases gradually. The Shock if Unstableparameter is programmed to bypass ATP therapy and deliver shock therapyif the analysis of the ventricular rhythm is declared to be unstable.The Sustained Rate Duration (SRD) parameter enables the pulse generatorto override the Onset, Stability, or AFib Rate Threshold parameters'decision to inhibit therapy if the high rate continues throughout theprogrammed time period.

[0048] In one embodiment, if any of the following features, V Rate>ARate, AFib Rate Threshold, Brady Mode programmed to DDD(R), DDI(R),DVI(R), VDD(R), or AAI(R), Electrogram Storage Enabled for the atrialelectrode, or Atrial Rate EGM trace selected are programmed, the pulsegenerator will respond to atrial sensing whether an atrial lead isimplanted or not. If an atrial lead is not implanted, atrial data willbe erroneous.

[0049] The atrial rate may be used to both 1) inhibit therapy in thepresence of atrial fibrillation (AFib) or atrial flutter, and 2) tobypass Onset, Stability, and/or AFib Rate Threshold as inhibitors ifprogrammed On and the ventricular rate is faster than the atrial rate.

[0050] The V Rate>A Rate (ventricular rate greater than atrial rate)parameter can be programmed to bypass inhibitors (Onset, Stability,and/or AFib Rate Threshold) and initiate therapy in the event that theventricular rate is faster than the atrial rate. It can be programmed Onor Off. Analysis is made by comparing the average rate of the last 10ventricular intervals prior to the end of duration to the average rateof the last 10 atrial intervals prior to the end of duration and afterthe third fast ventricular interval. If fewer than 10 atrial intervalsare available, then the intervals available will be used to calculatethe average atrial rate. If the average ventricular rate is greater thanthe average atrial rate by at least 10 min⁻, the ventricular rate isdeclared to be faster than the atrial rate (indicated as True on theEpisode Detail report) and therapy will be initiated. If the ventricularrate is not greater than the atrial rate (indicated as False on theEpisode Detail report), then therapy may continue to be inhibited.

[0051] If therapy is inhibited, the V Rate>A Rate analysis continuesuntil either the ventricular rate is greater than the atrial rate or theother enhancements indicate therapy treatment, at which time therapywill be initiated.

[0052] Atrial rate detection is used to inhibit therapy in the eventthat the underlying cause of a moderately high ventricular rate is dueto ventricular response to fibrillation in the atrium. This isaccomplished by comparing the atrial rate to the preprogrammed AFib RateThreshold. If the atrial rate is greater than the AFib Rate Threshold,therapy will be withheld until the atrial rate drops below the AFib RateThreshold, or, if programmed On, the V Rate>A Rate is True, or theSustained Rate Duration timer expires. Programmable values for the AFibRate Threshold are Off or 200-400 min⁻.

[0053] When the AFib Rate Threshold is programmed separately from theStability parameter, a determination is made that the atrial rate isabove the AFib Rate Threshold in the following manner. At initiation ofventricular tachyarrhythmia detection, atrial analysis begins. Eachatrial interval is classified as faster or slower than the AFib RateThreshold interval. When 6 of the last 10 intervals are classified asfaster than the AFib Rate Threshold, the device declares atrialfibrillation to be present. Therapy will be withheld, and the atrialrate will continue to be examined; as long as 4 of 10 intervals remainclassified as fast, atrial fibrillation continues to be present. Whenprogrammed with Stability the ventricular rhythm is also considered inthe decision.

[0054] If AFib Rate Threshold and Stability are both programmed On, thedevice will analyze both parameters to determine if therapy is to bedelivered or withheld. If the atrial rate is greater than the AFib RateThreshold and the ventricular rhythm is classified as unstable, theventricular rhythm is declared to be due to atrial fibrillation.

[0055] The atrial rate is declared to be above the AFib Rate Thresholdin the manner discussed above. Ventricular stability is then checkedand, if unstable, therapy will be inhibited. In the event that therapyis not delivered, the atrial rate will continue to be examined; as longas 4 of 10 intervals remain classified as fast, atrial fibrillationcontinues to be present. Therapy is inhibited until the atrial ratedrops below the AFib Rate Threshold, the ventricular rhythm becomesstable, or if programmed On, V Rate>A Rate is true or Sustained RateDuration times out. An illustration of AFib Rate Threshold and Stabilityinteraction is shown in FIG. 6.

[0056] In one embodiment, the device will initiate therapy when a stablerhythm is declared; and will initiate therapy for an unstable rhythmwhen it is determined that the atrial rate is less than the AFib RateThreshold.

[0057] If the AFib Rate Threshold, Stability, and Onset parameters areall programmed On, to initiate therapy the rhythm must have a suddenonset and either the ventricular rate must be stable or the atrial ratemust be less than the AFib Rate Threshold. If the detection enhancementV Rate>A Rate is programmed On and is determined to be True, it takesprecedence over all other inhibitor enhancements.

[0058] The Onset enhancement measures the rate of transition inventricular rhythm from slow rates to tachycardia. It is intended todifferentiate physiologic sinus tachycardias, which typically beginslowly, from pathologic tachycardias, which typically begin abruptly.With Onset enabled, the device inhibits therapy in the lowesttachycardia rate zone if the rate increase is gradual. Programmablevalues for Onset are Off or 9-50% or 50-250 ms.

[0059] The Onset enhancement is measured using ventricular rate only andmay be programmed as a percentage of cycle length, or as an intervallength in ms. It is limited to the lowest zone of a multizoneconfiguration. The selected Onset value represents the minimumdifference that must exist between intervals that are below the lowestprogrammed rate threshold and intervals that are above the lowestprogrammed rate threshold. The pulse generator performs Onsetcalculations (even when it is programmed Off) for all episodes exceptinduced episodes, and stores the measured Onset results from a two-stagecalculation in therapy history. This stored data (in ms and %) is usefulin programming an appropriate Onset value.

[0060] When a detection window becomes satisfied (episode declared andmemory allotted for history data storage), the pulse generator beginscalculating for sudden onset in a two-stage sequence.

[0061] The first stage measures the intervals prior to the start of theepisode and locates the pair of adjacent intervals (pivot point) wherethe cycle length decreased the most. If the decrease in cycle length isequal to or greater than the programmed Onset value, the first stagedeclares onset to be sudden.

[0062] The second stage then compares additional intervals; if thedifference between the average interval before the pivot point and 3 outof the first 4 intervals following the pivot point is equal to orgreater than the programmed Onset threshold, the second stage declaresonset to be sudden.

[0063] If both stages declare the rhythm sudden, therapy will beinitiated. If either stage indicates a gradual onset, initial therapywill be inhibited in the lowest zone; then therapy will be deliveredonly if the rate accelerates to a higher zone, information from theatrial lead determines that the ventricular rate is faster than theatrial rate (V Rate>A Rate programmed On), or the Sustained RateDuration (SRD) timer expires.

[0064] Stability analysis is used to distinguish unstable (irregular)ventricular rhythms from stable (regular) ventricular rhythms. This isaccomplished by measuring the degree of variability of the tachycardiaR-R intervals. This degree of variability, when used by itself, mayallow the device to distinguish conducted atrial fibrillation (which mayproduce greater R-R variability) from monomorphic VT (which is typicallystable). It also may be used to differentiate MVTs (which are paceterminable) from polymorphic VTs and VF (which are typically not paceterminable). Based on the patient's needs, the physician may choose toprogram Stability as an inhibitor to prevent therapy for atrialfibrillation, or use stability analysis to direct the type of therapy tobe delivered (Shock if Unstable).

[0065] The stability analysis algorithm calculates R-R intervaldifferences. These differences are calculated throughout Duration, andan average difference is also calculated. When Duration expires, rhythmstability is evaluated by comparing the current average difference tothe programmed Stability and Shock if Unstable thresholds. If theaverage difference is greater than the programmed thresholds, the rhythmis declared unstable. Independent thresholds are available for theStability (to inhibit) or Shock if Unstable functions; both cannot beprogrammed in the same zone. Programmable values for Stability Analysiscan be Off or 6-120 ms.

[0066] In one embodiment, the pulse generator performs stabilitycalculations for all episodes (even when Stability is programmed Off)and stores the results in therapy history. This stored data is useful inselecting an appropriate stability threshold.

[0067] The Stability parameter can be used to identify rapid rhythmsoriginating in the atrium, such as atrial fibrillation, that may resultin unstable rhythms in the ventricle whose rate exceeds the lowest ratethreshold and which should not be treated. If a rhythm is declaredstable when Duration expires, programmed therapy will be delivered. Ifthe rhythm is declared unstable, the parameter will render a decision towithhold therapy. This is intended for rhythms originating in the atriumthat may result in unstable rhythms in the ventricle whose rate exceedsthe lowest rate threshold. At the end of initial Duration, if atachycardia is declared unstable and therapy is inhibited, the pulsegenerator continues to evaluate for stability on each new detectedinterval. It will evaluate for stability as long as the zone's detectionwindow remains satisfied, or until the V Rate>A Rate declares theventricular rate greater than the atrial rate, or the Sustained RateDuration (SRD) timer has expired (if programmed On). If the rate becomesstable before V Rate>A Rate is True or the SRD timer has expired, theprogrammed therapy is initiated immediately.

[0068] In one embodiment, Stability can be inhibited only in the lowestzone of a two or three-zone configuration; it may be used in conjunctionwith other detection enhancements.

[0069] In one embodiment, Stability can be programmed to Shock IfUnstable. In this programming mode, the stability analysis helpsdetermine if ATP therapy should be bypassed in preference for the firstprogrammed shock therapy (which may be low or high energy) for the zone.Dynamic ventricular arrhythmias such as polymorphic VT or VF may besensed at a rate lower than the highest rate threshold and can beclassified as unstable. Since the sensed rhythm may be detected in alower zone in which ATP may be programmed, the stability analysis may beused to skip over the programmed ATP therapies and instead provideshocks to the patient. Stability is evaluated on eachdetection/redetection cycle, including evaluation between bursts of anATP scheme. Once a shock has been delivered in an episode, the Shock IfUnstable function no longer affects therapy selection.

[0070] The Shock If Unstable feature may be used only in the VT zone ofa two-zone configuration or three-zone configuration. It cannot beprogrammed in a two-zone configuration if Stability or Onset is alreadyprogrammed On, or if Post-shock Stability or AFib Rate Threshold isprogrammed On.

[0071] When Stability is programmed to inhibit, it may be combined withthe Onset parameter to provide even greater specificity incharacterizing arrhythmias. The enhancements can be programmed such thatto initiate therapy, both Onset And Stability must indicate to treat, orsuch that if either Onset Or Stability indicates to treat, therapy isdelivered (see FIGS. 7 and 8 for representative Onset, Stability andAFib Rate combinations and the suggested therapy).

[0072] If the combination programmed is Onset And Stability, therapy isinhibited if either parameter indicates that therapy should be withheld;that is, the rhythm is gradual Or unstable (the And condition to treatis not satisfied). If the combination programmed is Onset Or Stability,therapy is inhibited immediately at the end of Duration only if bothparameters indicate that therapy should be withheld; that is, the rhythmis gradual and unstable (the Or condition to treat is not satisfied). Ineither case, therapy is initiated only if the And/Or conditions to treatare satisfied. When these two combinations (And/Or) are used inconjunction with Sustained Rate Duration (SRD), and the And/Orconditions are not satisfied, therapy is inhibited until V Rate>A Rateis True or SRD times out.

[0073] Sustained Rate Duration (SRD) allows the programmed therapy to bedelivered when a tachycardia is sustained for a programmed period oftime beyond Duration, but the programmed therapy inhibitors (AFib RateThreshold, Onset, and/or Stability) indicates to withhold therapy. FIG.9 illustrates SRD in relation to the inhibitor enhancements. It is notused in conjunction with Shock If Unstable. In one embodiment,programmable values for SRD are Off or 10 to 60 seconds.

[0074] SRD is used only when an inhibitor enhancement is programmed On.If an inhibitor is withholding therapy delivery and the Rate criterionin the lowest zone is maintained, the SRD timer begins at the end ofDuration. If the detection window in the lowest zone is maintained forthe programmed SRD period, the programmed therapy will be delivered atthe end of the SRD period. If the rate accelerates to a higher zone andthe Duration for the higher zone expires, therapy is initiated in thatzone without waiting for SRD to time out. If SRD is programmed Off, anSRD timer will not start when Duration expires.

[0075] In one embodiment, detection enhancements are available in onlycertain zones of a multi-zone configuration. One such embodiment isshown in FIG. 5.

[0076] A representative three zone configuration is shown in FIG. 4. Inthe embodiment shown in FIG. 4, system 10 includes up to threetachyarrhythmia zones (labeled as VT-1, VT, and VF). In one suchembodiment, such as is shown in FIG. 4, each zone is identified ondisplay 24 with its label 70 and its rate threshold 72. In theembodiment shown in FIG. 4, label 70 and its associated rate threshold72 are displayed within a zone rate bar 74. In addition, a detectionsummary for each zone is displayed within detection button 76 for thatzone and a therapy summary for each zone is displayed within therapybutton 78 for that zone.

[0077] In one embodiment, the user accesses the detection parameters fora zone by selecting the respective detection button 76 and accesses thetherapy parameters for a zone by selecting the respective therapy button78. The user selects the rate threshold value in order to change therate threshold for that zone. And the number of zones tachyarrhythmiazones can be modified by selecting one of the number buttons beneath the“# Zones” label.

[0078] In one embodiment, if parameter settings have changed but havenot yet been programmed into the pulse generator, hatch marks (////)will appear in the summary area. When the values are programmed, thehatch marks disappear.

[0079] A subset of zone configuration information is displayed when thesystem summary and quick check screens are visible, which allows ashortcut to the detection and/or therapy parameters screens. (Onlypresently programmed values are displayed; it does not display changeddata that has not yet been programmed into the device nor hatch marks.)In one embodiment, the user selects a shortcut icon to navigate to theTachy Parameters screen, which displays detailed information. If ashortcut icon appears dim, it indicates that a change to the number ofzones has not been programmed; thus a shortcut is not available to theparameter screens.

[0080] A brady therapy summary 80 is also visible in FIG. 4. This areadisplays the normal and post-shock bradycardia modes and rates.Additional bradycardia parameter settings may be viewed and changed byselecting the brady summary button when a shortcut icon is visible, orthe Brady Parameters tool. Depending on which toolbox screen is visible,this summary button may show just the rate/zone bar or may includeadditional information as is shown in FIG. 4.

[0081] Toolbox 82 displays various features depending on the chosentoolbox button. The features allow interaction with the pulse generatoras well as a review of data in pulse generator memory. Only one tool maybe selected at a time. (In one embodiment, the System Summary tool isselected when the application is initially accessed. However, if anepisode is in progress at initial interrogation, the EP Test screen willbe displayed.)

[0082] In the embodiment shown in FIG. 4, windows contain informationrelevant to a particular function. They may include names of pulsegenerator parameters and functions, value boxes to accommodate valuechanges, buttons to open additional windows, and buttons to cancelchanges or close the window. To remove the window from the display,select the button that initiates activity or select the Close or Cancelbutton.

[0083] Message windows are used to provide feedback during communicationsessions. Some require action as indicated in the window beforecontinuing the session, while others simply relay information withoutrequiring further action or show status of an activity. Many messagewindows have a Cancel or Close button; select the desired button tocancel the action being performed as explained in the message and/orclose the window.

[0084] In the embodiment shown in FIG. 4, ECG display 84 is alwaysvisible. ECG display 84 shows real-time surface ECG traces, as well asreal-time electrograms (EGMs) and event markers, which are useful inascertaining system performance. In one such embodiment, a 20-secondsnapshot of the ECG trace, electrograms, and markers can be printedautomatically; when the cursor is positioned over the ECG display thecursor changes to a camera icon; click the left trackball key to“capture” the trace. The printed trace shows 10 seconds before and 10seconds after the moment of command.

[0085] In one embodiment, annotated event markers identify certainintrinsic cardiac and device-related events, and provide informationsuch as sensed/paced events, decision of detection criteria, and therapydelivery. The markers are displayed on ECG display 84.

[0086] In one embodiment, real-time electrograms can be transmitted fromthe pace/sense or shocking electrodes to evaluate lead system integritysuch as lead fractures, insulation breaks, or dislodgments.

[0087] The number of zones, the zones' rate thresholds, and values fordetection, redetection, and detection enhancement parameters can beprogrammed from the Zone Configuration display in FIG. 4 in thefollowing manner.

[0088] First, select Tachy Parameters button 86 from toolbox 82 todisplay the zone configuration area and the selected zone's parameters.Next, change the number of zones by selecting the desired number (1, 2,or 3) from the #Zones column. The zone configuration will display theselected number of zones with hatch marks overlaying the new zones,which have not been programmed into the device yet. Third, change therate threshold using either select box 72 from zone/rate bar 74 or viathe zone's detection button 76. If a zone's detection button 76 has beenselected, the initial and redetection parameters 88 are displayed. FIG.4 illustrates the initial and redetection parameters associated with theVT-1 zone, while FIG. 15 illustrates the initial and redetectionparameters associated with the VT zone. Detection enhancement rhythmdiscrimination categories 90 (see FIGS. 4 and 15) are displayed as wellfor those zones in which enhancements are available.

[0089] Next, change any of the desired initial or redetectionparameters. In one embodiment, hatch marks overlay the zone's detectionbutton 76 until the changed parameters have been programmed into thepulse generator. Note: As parameter values are changed, the informationicon and/or stop sign icon may appear at the top of the main applicationscreen to inform of potential parameter interactions. Modify parametersas required to get around these objections. More information onparameter interaction can be found in “System and Method for Detectingand Displaying Parameter Interactions,” filed herewith.

[0090] Next, select the magnifying-glass icon ro display enhancementparameter details. Detection enhancement details for VT-1 zone are shownin FIGS. 4, 10 and 14 Detection enhancement details for VT zone areshown in FIGS. 15 and 16.

[0091] As noted above, detection enhancement parameters can be moreeasily programmed by identifying the type of rhythm discriminationdesired and associating the clinical rhythms with particular detectionenhancements. In one embodiment, the types of clinical rhythms include:atrial tachyarrhythmia, sinus tachycardia, and polymorphic VT. FIG. 11illustrates rhythm discrimination available per zone in multizoneconfigurations.

[0092] When a rhythm discrimination is selected, preselected values aredisplayed for the parameters that are suitable for discriminating thatrhythm (see FIGS. 12 and 13). From a zone's detection screen, detectionparameters can be turned On by selecting the Detection Enhancements Onor Off value box, or by selecting the individual rhythm types (see FIGS.10, 14 and 16).

[0093] To access the detection enhancement parameters, one would selectthe value box in the Change column next to the text “DetectionEnhancements” in a zone's detection window. If Select On is chosen, theboxes next to the type of rhythm discriminations will be checked. InSelect Off is chosen, the boxes remain unchecked.

[0094] One can select individual discrimination types. To select ordeselect individual discrimination types, select the box next to thediscrimination type to check or uncheck the box.

[0095] One can also view detection enhancement window 92 shown in FIGS.10, 14 and 16. In one embodiment, detection enhancement windows 92 canbe viewed by selecting magnifying-glass icon 94 of FIGS. 4 and 15. Therespective individual parameters and values are displayed for whicheverdiscrimination type is selected. Parameter values can then be adjustedfrom this window. The discrimination types are automatically checked andunchecked according to the changes made in the enhancement window.

[0096] Window 92 is closed when the parameters values are as desired.

[0097]FIG. 17 shows a programming screen 1700 with a button 1710 forenabling rate smoothing. One example of a rate smoothing algorithm andsystem is provided in U.S. Pat. No. 4,562,841 entitled: ProgrammableMulti-mode Cardiac Pacemaker, by Brockway et al., issued Jan. 7, 1986,and which is hereby incorporated by reference in its entirety. The ratesmoothing function prevents the rate interval from changing by more thana predetermined percentage on a cycle-to-cycle basis.

[0098] Some patients favor devices executing a rate smoothing algorithm,because regulation of the ventricular pacing rate seems to provide morecomfortable pacing. Furthermore, rate smoothing is believed to reducethe amount of ventricular tachycardia and ventricular fibrillationepisodes by elimination of short-long-short induction sequences.

[0099] Toolbox 82 displays various features depending on the chosentoolbox button. The features allow interaction with the pulse generatoras well as a review of data in pulse generator memory. In the embodimentshown in FIG. 17, windows contain information relevant to a particularfunction. They may include names of pulse generator parameters andfunctions, value boxes to accommodate value changes, buttons to openadditional windows, and buttons to cancel changes or close the window.To remove the window from the display, select the button that initiatesactivity or select the Close or Cancel button.

[0100] In one embodiment of the present programming system, the screen1700 including the button 1710 for enabling rate smoothing is availablefor selection by the user. In one embodiment, the rate smoothing button1710 toggles between enabling and disabling of rate smoothing. Forexample, initially, when rate smoothing is disabled, the button 1710reads “enable rate smoothing.” Upon depressing the button with a mouseor other pointing device, the programmer sends a signal initiating ratesmoothing in the implantable device. Once the rate smoothing function isprogrammed, the software operating on the programmer changes the button1710 to read “disabled rate smoothing.” If the user of the programmerpresses the button it will send a signal to the programmable device todisable rate smoothing. The button 1710 will then be updated to read“enable rate smoothing.”

[0101]FIG. 18 shows another embodiment of a programming screen 1800 ofthe present programming system, where a single “enable rate control”button 1810 selects a number of different parameters to assist thedoctor in programming the device for rate control in a straightforwardand efficacious manner. For example, in one embodiment, selecting therate control button 1810 enables the following features of theprogrammable pulse generator:

[0102] rate smoothing;

[0103] atrial tachycardia response; and

[0104] atrial flutter response.

[0105] In one embodiment, default parameter values are provided for eachfeature, where any number of values can be used for up-smoothing anddown-smoothing. For example, for up-smoothing, the rate interval changecan be 25 percent, while for down-smoothing the rate interval change canbe set from 9 to 12 percent. In one embodiment, selecting the “enablerate control” button 1810 selects the following parameter values:

[0106] rate smoothing:

[0107] For up-smoothing a rate interval change of 25 percent percentageand a rate interval change for down-smoothing of six (6) to nine (9)percent of the previous interval.

[0108] atrial tachy response (ATR):

[0109] 4 entry count;

[0110] 4 exit count;

[0111] 8 duration;

[0112] 70 fall-back rate;

[0113] DDIR mode;

[0114] atrial flutter response (AFR):

[0115] 170 beats per minute; and

[0116] rate threshold:

[0117] 170 beats per minute.

[0118] In this embodiment, the atrial flutter response is set to thesame value as a rate threshold (170 beats per minute) so that the devicewill obtain immediate disassociation with one fast atrial beat without acomplete mode switch until it is necessary and sustained. The exemplaryparameter values listed above may be varied without departing from thescope of the present invention.

[0119] A shock therapy system such as system 10 provides the ease of useof selecting detection enhancements as a function of clinical rhythmwhile, at the same time, providing layers of complexity, so that forthose that are used to programming the specific parameters can do so.Newer users benefit from the expertise of the designers by letting theunderlying expert systems set the appropriate parameters. Experiencedusers benefit by only having to modify the entries that differ fromthose preset by the expert system.

[0120] Although specific embodiments have been illustrated and describedherein, it will be appreciated by those of ordinary skill in the artthat any arrangement which is calculated to achieve the same purpose maybe substituted for the specific embodiment shown. This application isintended to cover any adaptations or variations of the presentinvention. Therefore, it is intended that this invention be limited onlyby the claims and the equivalents thereof.

What is claimed is:
 1. A system for delivering shocks to a heart, thesystem comprising: a programmer including: a selection module adapted toselect one or more detection enhancements from a plurality ofpredetermined detection enhancements; a parameter modification modulecoupled to the selection module, the parameter modification moduleadapted to receive parameters related to the selected one or moredetection enhancements; and a communication module coupled to theselection module and the parameter modification module, thecommunication module adapted to program the parameters into a medicaldevice.
 2. The system of claim 1, wherein the medical device comprises adefibrillator.
 3. The system of claim 2, wherein the defibrillatorcomprises an implantable defibrillator.
 4. The system of claim 1,wherein the selection module comprises a display and a user interface toselect one or more detection enhancements from the plurality ofpredetermined detection enhancements.
 5. The system of claim 4, whereinthe display comprises: a zone rate bar presenting a plurality ofpredetermined arrhythmia zones each associated with one or more of theplurality of predetermined detection enhancements; detection buttonseach associated with one arrhythmia zone of the plurality ofpredetermined arrhythmia zones to display a detection parameter summaryfor that one arrhythmia zone and to access to the detection parametersfor that one arrhythmia zone; and therapy buttons each associated withone arrhythmia zone of the plurality of predetermined arrhythmia zonesto display a therapy parameter summary for that one arrhythmia zone andto access to the therapy parameters for that one arrhythmia zone.
 6. Thesystem of claim 5, wherein the display comprises number buttons forchanging a number of the arrhythmia zones in the plurality ofpredetermined arrhythmia zones.
 7. The system of claim 5, wherein thezone rate bar presenting the plurality of arrhythmia zones comprises azone rate bar presenting a plurality of tachyarrhythmia zones, andwherein the display further comprises a brady therapy summary to presentbradycardia therapy parameters and access to the bradycardia therapyparameters.
 8. The system of claim 5, wherein the zone rate barcomprises labels each representing one of the plurality of arrhythmiazones.
 9. The system of claim 8, wherein the zone rate bar furthercomprises changeable rate threshold values each associated with one ofthe plurality of arrhythmia zones.
 10. The system of claim 8, whereinthe zone rate bar comprises labels representing at least one of atrialtachyarrhythmia, sinus tachycardia, polymorphic ventriculartachyarrhythmia, and ventricular fibrillation.
 11. A method fordelivering shocks to a heart, the method comprising: displaying one ormore predetermined clinical rhythms for selection; receiving a clinicalrhythm selected from the displayed one or more predetermined clinicalrhythms; identifying one or more detection enhancements associated withthe selected clinical rhythm, the one or more detection enhancementseach being a set of rules for determining when to deliver one or more ofthe shocks; and setting detection enhancement parameters associated withthe identified one or more detection enhancements; and programming thedetection enhancement parameters into a device to perform the identifiedone or more detection enhancements.
 12. The method of claim 11, whereinsetting the detection enhancement parameters comprises setting thedetection enhancement parameters to stored detection enhancementparameter values.
 13. The method of claim 11, wherein setting thedetection enhancement parameters comprises determining whether toreceive a modification to the detection enhancement parameters.
 14. Themethod of claim 13, wherein setting the detection enhancement parametersfurther comprises receiving the modification to the detectionenhancement parameters through a user interface.
 15. The method of claim11, wherein the shocks comprise ventricular shocks, and programming thedetection enhancement parameters into the device comprises programmingthe detection enhancement parameters into a defibrillator to perform atleast one of delaying a delivery of one of the shocks, inhibiting adelivery of one of the shocks, bypassing an inhibition of a delivery ofone of the shocks, and bypassing another therapy in favor of a deliveryof one of the shocks.
 16. The method of claim 15, wherein identifyingthe one or more detection enhancements comprises selection of one ormore of: delivering one of the shocks if a ventricular rate is greaterthan an atrial rate; inhibiting a delivery of one of the shocks if theatrial rhythm is fast; inhibiting a delivery of one of the shocks if theventricular rate is unstable; inhibiting a delivery of one of the shocksif a heart rate increases gradually; delivering one of the shocks if ananalysis of the ventricular rhythm is determined to be unstable; anddelivering one of the shocks if a high heart rate continues throughout aprogrammed time period.
 17. The method of claim 11, wherein displayingthe one or more predetermined clinical rhythms comprises displaying oneor more tachyarrhythmia zones.
 18. The method of claim 17, whereindisplaying the one or more tachyarrhythmia zones comprises displayingone or more of atrial tachyarrhythmia, sinus tachycardia, polymorphicventricular tachyarrhythmia, and ventricular fibrillation.
 19. A cardiacshock therapy system comprising: means for receiving a selection of oneor more detection enhancements from a plurality of predetermineddetection enhancements; and means for determining parameters related tothe selected one or more detection enhancements.
 20. The cardiac shocktherapy system of claim 19, further comprising means for determining ashock delivery by performing the selected one or more detectionenhancements.
 21. The cardiac shock therapy system of claim 19, whereinthe means for determining parameters comprises means for determiningwhether to receive a modification to the parameters.
 22. The cardiacshock therapy system of claim 19, wherein the means for receiving theselection of one or more detection enhancements also comprises a userinterface means.
 23. The cardiac shock therapy system of claim 22,wherein the user interface means comprises means for presenting aplurality of arrhythmia zones each associated with one or more of theplurality of predetermined detection enhancements.
 24. The cardiac shocktherapy system of claim 23, wherein the user interface means comprisesmeans allowing for changing a number of the arrhythmia zones in theplurality of arrhythmia zones.
 25. The cardiac shock therapy system ofclaim 23, wherein the means for presenting the plurality of arrhythmiazones comprises means for displaying rate threshold values each of whichis associated with one of the plurality of arrhythmia zones and forallowing for changing of the rate threshold value for the one of theplurality of arrhythmia zones.
 26. The cardiac shock therapy system ofclaim 22, wherein the means for determining parameters also comprises afurther user interface means.
 27. The cardiac shock therapy system ofclaim 26, wherein the further user interface means comprises: means fordisplaying a detection parameter summary associated with the one of theplurality of arrhythmia zones and allowing for modifications of thedetection parameters associated with that one of the plurality ofarrhythmia zones; and means for displaying a therapy parameter summaryassociated with the one of the plurality of arrhythmia zones andallowing for modifications of the therapy parameters associated withthat one of the plurality of arrhythmia zones.